Summary

• Cisco has released software updates that address these vulnerabilities. [Workarounds that mitigate these vulnerabilities are available.] This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-crafted-tcp.

Affected Products

• Vulnerable Products

  This issue affects all Cisco devices running Cisco IOS software. To be affected, devices must be configured to process Internet Protocol version 4 (IPv4) packets and receive TCP packets. Devices which run only Internet Protocol version 6 (IPv6) are not affected.

  This vulnerability is present in all unfixed versions of Cisco IOS software, including versions 9.x, 10.x, 11.x and 12.x.

  To determine the software running on a Cisco product, log in to the device and issue the "show version" command to display the system banner. Cisco IOS software will identify itself as "Internetwork Operating System Software" or simply "IOS". On the next line of output, the image name will be displayed between parentheses, followed by "Version" and the IOS release name. Other Cisco devices will not have the "show version" command or will give different output.

  The following example identifies a Cisco product running Cisco IOS release 12.2(14)S16 with an installed image name of C7200-IS-M:

  Cisco Internetwork Operating System Software 
  IOS (tm) 7200 Software (C7200-IS-M), Version 12.2(14)S16, RELEASE SOFTWARE (fc1)

  The release train label is "12.2".

  The next example shows a product running IOS release 12.3(7)T12 with an image name of C7200-IK9S-M:

  Cisco IOS Software, 7200 Software (C7200-IK9S-M), Version 12.3(7)T12, RELEASE SOFTWARE  (fc1)
  

  Additional information about Cisco IOS Banners is available at:

  http://www.cisco.com/web/about/security/intelligence/ios-ref.html

  Products Confirmed Not Vulnerable

  Cisco products that do not run IOS are unaffected by this vulnerability.

  Cisco IOS-XR is not affected.

  No other Cisco products are currently known to be affected by this vulnerability.

Details

• TCP is the transport layer protocol designed to provide connection-oriented, reliable delivery of a data stream. To accomplish this, TCP uses a mixture of flags to indicate state and sequence numbers to identify the order in which the packets are to be reassembled. TCP also provides a number, called an acknowledgement number, that is used to indicate the sequence number of the next packet expected. The full specification of the TCP protocol can be found at http://www.ietf.org/rfc/rfc0793.txt .

  Cisco IOS devices that are configured to receive TCP packets are exposed to this issue. This Advisory does not apply to traffic that is transiting the device.

  Certain crafted packets destined to an IPv4 address assigned to a physical or virtual interface on a Cisco IOS device may cause the device to leak a small amount of memory. Over time, such a memory leak may lead to memory exhaustion and potentially degraded service.

  Although this is an issue with TCP, it is not required to complete the TCP 3-way handshake in order for the memory leak to be triggered. Therefore, TCP packets with a spoofed source address may trigger the leak.

  The following document contains additional information on how to identify if your router is suffering from a memory leak in Processor memory:

  http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a6f3a.shtml#tshoot2

Workarounds

• Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory:

  https://sec.cloudapps.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070124-crafted-tcp

  Note: Configuring VTY access-class filters is not an effective mitigation strategy for this vulnerability.

  Infrastructure ACLs (iACL)

  Although it is often difficult to block traffic transiting your network, it is possible to identify traffic which should never be allowed to target your infrastructure devices and block that traffic at the border of your network. Infrastructure ACLs are considered a network security best practice and should be considered as a long-term addition to good network security as well as a workaround for this specific vulnerability. The ACL example shown below should be included as part of the deployed infrastructure access-list which will protect all devices with IP addresses in the infrastructure IP address range.

  A sample access list for devices running Cisco IOS is below:

  
  !--- Permit TCP services from trust hosts destined 
  !--- to infrastructure addresses.
  
  
  access-list 150 permit tcp TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK
  
  
  !--- Deny TCP packets from all other sources destined to infrastructure addresses.
  
  
  access-list 150 deny   tcp any INFRASTRUCTURE_ADDRESSES MASK
  
  
  !--- Permit all other traffic to transit the device.
  
  
  access-list 150 permit IP any any
  
  interface serial 2/0
    ip access-group 150 in

  The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists. This white paper can be obtained here: http://www.cisco.com/warp/public/707/iacl.html

  Receive ACLs (rACL)

  For distributed platforms, Receive ACLs may be an option starting in Cisco IOS Software Versions 12.0(21)S2 for the 12000 (GSR), 12.0(24)S for the 7500, and 12.0(31)S for the 10720. The Receive ACL protects the device from harmful traffic before the traffic can impact the route processor. Receive ACLs are designed to only protect the device on which it is configured. On the 12000, transit traffic is never affected by a receive ACL. Because of this, the destination IP address "any" used in the example ACL entries below only refer to the router's own physical or virtual IP addresses. On the 7500 and 10720, transit traffic with IP options set will be subject to the Receive ACL and permitted or denied accordingly. Receive ACLs are considered a network security best practice, and should be considered as a long-term addition to good network security, as well as a workaround for this specific vulnerability. The white paper entitled "GSR: Receive Access Control Lists" will help you identify and allow legitimate traffic to your device and deny all unwanted packets: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a0a5e.shtml

  The following is the receive path ACL written to permit this type of traffic from trusted hosts:

  
  !--- Permit tcp services from trusted hosts allowed to the RP.
     
                                                  
  access-list 151 permit tcp TRUSTED_ADDRESSES MASK any                                                        
  
  
  !--- Deny tcp services from all other sources to the RP.
                                                           
  
  access-list 151 deny   tcp any any                                                                           
  
  
  !--- Permit all other traffic to the RP.
                                                                           
  
  access-list 151 permit ip any any                                                                            
  
  
  !--- Apply this access list to the 'receive' path.
                                                                 
  
  ip receive access-list 151

  Control Plane Policing (CoPP)

  The Control Plane Policing (CoPP) feature may be used to mitigate this vulnerability. In the following example, only TCP traffic from trusted hosts and with 'receive' destination IP addresses is permitted to reach the route processor (RP). All other 'transit' IP traffic is unaffected.

  It should be noted that dropping traffic from unknown or untrusted IP addresses may affect hosts with dynamically assigned IP addresses from connecting to the Cisco IOS device.

  access-list 152 deny   tcp TRUSTED_ADDRESSES MASK any
  access-list 152 permit tcp any any
  access-list 152 deny  ip any any
  !
  class-map match-all permit-tcp-class
   match access-group 152
  !
  !
  policy-map permit-tcp-policy
   class permit-tcp-class
    drop
  !
  control-plane
   service-policy input permit-tcp-policy

  In the above CoPP example, the ACL entries that match the exploit packets with the "permit" action result in these packets being discarded by the policy-map "drop" function, while packets that match the "deny" action are not affected by the policy-map drop function.

  Please note that in the 12.2S and 12.0S Cisco IOS trains the policy-map syntax is different:

  policy-map permit-tcp-policy                                                                             
   class class permit-tcp-class                                                                            
    police 32000 1500 1500 conform-action drop exceed-action drop

  CoPP is available in Cisco IOS release trains 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T.

  Additional information on the configuration and use of the CoPP feature can be found at the following URL:

  http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6642/prod_white_paper0900aecd804fa16a.html

  Anti-spoofing

  The Unicast Reverse Path Forwarding (Unicast RPF or uRPF) feature helps to mitigate problems that are caused by spoofed IP source addresses. It is available on Cisco routers and firewalls. For further details, please refer to:

  http://www.cisco.com/en/US/docs/ios/11_1/feature/guide/uni_rpf.html

  By enabling Unicast Reverse Path Forwarding (uRPF), all spoofed packets will be dropped at the first device. To enable uRPF, use the following commands.

  router(config)#ip cef                                                                                     
  router(config)#interface interface #                                                                      
  router(config-if)#ip verify unicast source reachable-via rx
  

  BGP and BTSH/GTSM

  Depending on your release of software, it may be possible to protect your BGP sessions from this memory leak. With the introduction of CSCee73956 ( registered customers only) , Cisco IOS has improved support for BTSH (BGP TTL Security Hack) to reduce, if not eliminate a risk of a memory leak due to this vulnerability. This functionality is also known as GTSM (Generalized TTL Security Mechanism) and documented in RFC 3682. This section refers to GTSM as applied to eBGP sessions only.

  Releases of Cisco IOS that contain CSCee73956 are protected from this attack against the BGP port (TCP port 179) only. Other ports should be protected accordingly.

  BTSH is not supported for iBGP sessions. BTSH was first introduced in Cisco IOS in 12.0(27)S, 12.3(7)T and 12.2(25)S. Note that the BTSH feature prior to CSCee73956 will not protect against this vulnerability.

  For more information on BTSH, please see: http://www.cisco.com/en/US/docs/ios/12_3t/12_3t7/feature/guide/gt_btsh.html

  BGP and MD5

  Configuring your Cisco IOS device for BGP MD5 authentication is a valid workaround to help protect the vulnerable device from crafted TCP packets sent against the BGP port (TCP 179).

  This can be configured as shown in the following example:

  router(config)#router bgp <AS_number>
  router(config-router)#neighbor <IP_address> password <enter_your_secret_here>
  

  It may be necessary to configure the same shared MD5 secret on both peers and at the same time. The introduction of CSCdx23494 ( registered customers only) will allow dynamically changing BGP MD5 keys without tearing the BGP session down.

  Although the BGP session will not be reset, BGP updates will not be processed until the same MD5 key is configured on both sides.

  Prior to the introduction of CSCdx23494 ( registered customers only) , failure to change the MD5 passwords at the same time will break the existing BGP session, and the new session will not get established until the exact same MD5 shared secret is configured on both devices. For a detailed discussion on how to configure BGP, refer to the following document:

  http://www.cisco.com/en/US/docs/ios/12_0/np1/configuration/guide/1cbgp.html

  Once the MD5 shared secret is configured, it is prudent to change it periodically. The exact period of time must fit within your company security policy.

Fixed Software

• When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

  In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center ("TAC") or your contracted maintenance provider for assistance.

  Each row of the Cisco IOS software table (below) describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix (the "First Fixed Release") and the anticipated date of availability for each are listed in the "Rebuild" and "Maintenance" columns. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).

  For more information on the terms "Rebuild" and "Maintenance," consult the following URL:

  http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

  Note: There are three IOS security advisories and one field notice being published on January 24, 2007. Each advisory lists only the releases which fix the issue described in the advisory. A combined software table is available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-bundle and can be used to choose a software release which fixes all security vulnerabilities published as of January 24, 2007. Links for the advisories and field notice are listed here.

  • https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-IOS-IPv6
  • https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-crafted-tcp
  • https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-crafted-ip-option
  • http://www.cisco.com/en/US/ts/fn/620/fn62613.html

  Requests for software rebuilds to include the change for Daylight Savings Time (DST) that will be implemented in March 2007 should be directed through the Technical Assistance Center (TAC), and this advisory should be used as reference.

  Major Release	Availability of Repaired Releases
  Affected 12.0-Based Release	Rebuild	Maintenance
  12.0	Vulnerable; migrate to 12.2(37) or later
  12.0DA	Vulnerable; migrate to 12.2(10)DA5 or later
  12.0DB	Vulnerable; migrate to 12.3(4)T13 or later
  12.0DC	Vulnerable; migrate to 12.3(4)T13 or later
  12.0S	12.0(31)S6
  	12.0(32)S4
  12.0SC	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.0SL	Vulnerable; migrate to 12.0(31)S6 or later
  12.0SP	Vulnerable; migrate to 12.0(31)S6 or later
  12.0ST	Vulnerable; migrate to 12.0(31)S6 or later
  12.0SX	12.0(25)SX11
  12.0SY		12.0(32)SY
  12.0SZ	Vulnerable; migrate to 12.0(31)S6 or later
  12.0T	Vulnerable; migrate to 12.2(37) or later
  12.0W	Not vulnerable
  12.0WC	12.0(5)WC15
  12.0WT	Not vulnerable
  12.0XA	Vulnerable; migrate to 12.2(37) or later
  12.0XB	Vulnerable; migrate to 12.2(37) or later
  12.0XC	Vulnerable; migrate to 12.2(37) or later
  12.0XD	Vulnerable; migrate to 12.2(37) or later
  12.0XE	Vulnerable; migrate to 12.1(26)E7 or later
  12.0XF	Not vulnerable
  12.0XG	Vulnerable; migrate to 12.2(37) or later
  12.0XH	Vulnerable; migrate to 12.2(37) or later
  12.0XI	Vulnerable; migrate to 12.2(37) or later
  12.0XJ	Vulnerable; migrate to 12.2(37) or later
  12.0XK	Vulnerable; migrate to 12.2(37) or later
  12.0XL	Vulnerable; migrate to 12.2(37) or later
  12.0XM	Vulnerable; migrate to 12.2(37) or later
  12.0XN	Vulnerable; migrate to 12.2(37) or later
  12.0XQ	Vulnerable; migrate to 12.2(37) or later
  12.0XR	Vulnerable; migrate to 12.2(37) or later
  12.0XS	Vulnerable; migrate to 12.1(26)E7 or later
  12.0XV	Vulnerable; migrate to 12.2(37) or later
  12.0XW	Not vulnerable
  Affected 12.1-Based Release	Rebuild	Maintenance
  12.1	Vulnerable; migrate to 12.2(37) or later
  12.1 AA	Vulnerable; migrate to 12.2(37) or later
  12.1 AX	Vulnerable; migrate to 12.2(25)EY4 or later
  12.1 AY	Vulnerable; migrate to 12.1(22)EA8 or later
  12.1 AZ	Vulnerable; migrate to 12.1(22)EA8 or later
  12.1 CX	Vulnerable; migrate to 12.2(37) or later
  12.1 DA	Vulnerable; migrate to 12.2(10)DA5 or later
  12.1 DB	Vulnerable; migrate to 12.3(4)T13 or later
  12.1 DC	Vulnerable; migrate to 12.3(4)T13 or later
  12.1E	12.1(26)E7
  	12.1(27b)E1
  12.1EA	12.1(22)EA8
  12.1EB	Vulnerable; contact TAC
  12.1EC	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.1EO	12.1EO | 12.1(19)EO6; available 22-Feb-07
  	12.1(20)EO3
  12.1EU	Vulnerable; migrate to 12.2(25)EWA6 or later
  12.1EV	Vulnerable; migrate to 12.2(27)SV4 or later
  12.1EW	Vulnerable; migrate to 12.2(25)EWA6 or later
  12.1EX	Vulnerable; migrate to 12.1(26)E7 or later
  12.1EY	Vulnerable; migrate to 12.1(26)E7 or later
  12.1EZ	Vulnerable; migrate to 12.1(26)E7 or later
  12.1T	Vulnerable; migrate to 12.2(37) or later
  12.1XA	Vulnerable; migrate to 12.2(37) or later
  12.1XB	Vulnerable; migrate to 12.2(37) or later
  12.1XC	Vulnerable; migrate to 12.2(37) or later
  12.1XD	Vulnerable; migrate to 12.2(37) or later
  12.1XE	Vulnerable; migrate to 12.1(26)E7 or later
  12.1XF	Vulnerable; migrate to 12.3(19) or later
  12.1XG	Vulnerable; migrate to 12.3(19) or later
  12.1XH	Vulnerable; migrate to 12.2(37) or later
  12.1XI	Vulnerable; migrate to 12.2(37) or later
  12.1XJ	Vulnerable; migrate to 12.3(19) or later
  12.1XL	Vulnerable; migrate to 12.3(19) or later
  12.1XM	Vulnerable; migrate to 12.3(19) or later
  12.1XP	Vulnerable; migrate to 12.3(19) or later
  12.1XQ	Vulnerable; migrate to 12.3(19) or later
  12.1XR	Vulnerable; migrate to 12.3(19) or later
  12.1XS	Vulnerable; migrate to 12.2(37) or later
  12.1XT	Vulnerable; migrate to 12.3(19) or later
  12.1XU	Vulnerable; migrate to 12.3(19) or later
  12.1XV	Vulnerable; migrate to 12.3(19) or later
  12.1XW	Vulnerable; migrate to 12.2(37) or later
  12.1XX	Vulnerable; migrate to 12.2(37) or later
  12.1XY	Vulnerable; migrate to 12.2(37) or later
  12.1XZ	Vulnerable; migrate to 12.2(37) or later
  12.1YA	Vulnerable; migrate to 12.3(19) or later
  12.1YB	Vulnerable; migrate to 12.3(19) or later
  12.1YC	Vulnerable; migrate to 12.3(19) or later
  12.1YD	Vulnerable; migrate to 12.3(19) or later
  12.1YE	Vulnerable; migrate to 12.3(19) or later
  12.1YF	Vulnerable; migrate to 12.3(19) or later
  12.1YH	Vulnerable; migrate to 12.3(19) or later
  12.1YI	Vulnerable; migrate to 12.3(19) or later
  12.1YJ	Vulnerable; migrate to 12.1(22)EA8 or later
  Affected 12.2-Based Release	Rebuild	Maintenance
  12.2		12.2(37)
  12.2B	Vulnerable; migrate to 12.3(4)T13 or later
  12.2BC	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.2BW	Vulnerable; migrate to 12.3(19) or later
  12.2BY	Vulnerable; migrate to 12.3(4)T13 or later
  12.2BZ	Vulnerable; migrate to 12.3(7)XI8 or later
  12.2CX	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.2CY	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.2CZ	Vulnerable; contact TAC
  12.2DA	12.2(10)DA5
  	12.2(12)DA10
  12.2DD	Vulnerable; migrate to 12.3(4)T13 or later
  12.2DX	Vulnerable; migrate to 12.3(4)T13 or later
  12.2EU	Vulnerable; migrate to 12.2(25)EWA6 or later
  12.2EW	Vulnerable; migrate to 12.2(25)EWA6 or later
  12.2EWA	12.2(25)EWA6
  12.2EX	12.2(25)EX1
  12.2EY	12.2(25)EY4
  12.2EZ	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2FX	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2FY	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2FZ	All 12.2FZ releases are fixed
  12.2IXA	Vulnerable; migrate to 12.2(18)IXD; available 30-April-07
  12.2IXB	Vulnerable; migrate to 12.2(18)IXD; available 30-April-07
  12.2IXC	Vulnerable; migrate to 12.2(18)IXD; available 30-April-07
  12.2JA	Vulnerable; migrate to 12.3(8)JA2 or later
  12.2JK	Vulnerable; migrate to 12.4(4)T4 or later
  12.2MB	Vulnerable; migrate to 12.2(25)SW8 or later
  12.2MC	Vulnerable; migrate to 12.3(11)T11 or later
  12.2S	12.2(25)S12; Available 12-Feb-07
  12.2SB	12.2(28)SB2	12.2(31)SB
  12.2SBC	12.2(27)SBC5
  12.2SE		12.2(35)SE
  12.2SEA	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2SEB	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2SEC	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2SED	Vulnerable; migrate to 12.2(25)SEE1 or later
  12.2SEE	12.2(25)SEE1
  12.2SEF	12.2(25)SEF1
  12.2SEG	All 12.2SEG releases are fixed
  12.2SG		12.2(37)SG; Available 25-Apr-07
  12.2SGA	All 12.2SGA releases are fixed
  12.2SO	12.2(18)SO7
  12.2SRA	All 12.2SRA releases are fixed
  12.2SRB	All 12.2SRB releases are fixed
  12.2SU	Vulnerable; migrate to 12.4(8) or later
  12.2SV	12.2(27)SV4
  	12.2(28)SV1
  	12.2(29)SV1
  12.2SW	12.2(25)SW8
  12.2SX	Vulnerable; migrate to 12.2(18)SXD7a or later
  12.2SXA	Vulnerable; migrate to 12.2(18)SXD7a or later
  12.2SXB	Vulnerable; migrate to 12.2(18)SXD7a or later
  12.2SXD	12.2(18)SXD7a
  12.2SXE	12.2(18)SXE6
  12.2SXF	12.2(18)SXF5
  12.2SY	Vulnerable; migrate to 12.2(18)SXD7a or later
  12.2SZ	Vulnerable; migrate to 12.2(25)S12 or later; Available 12-Feb-07
  12.2T	Vulnerable; migrate to 12.3(19) or later
  12.2TPC	Vulnerable; contact TAC
  12.2XA	Vulnerable; migrate to 12.3(19) or later
  12.2XB	Vulnerable; migrate to 12.3(19) or later
  12.2XC	Vulnerable; migrate to 12.3(4)T13 or later
  12.2XD	Vulnerable; migrate to 12.3(19) or later
  12.2XE	Vulnerable; migrate to 12.3(19) or later
  12.2XF	Vulnerable; migrate to 12.3(13a)BC6 or later
  12.2XG	Vulnerable; migrate to 12.3(19) or later
  12.2XH	Vulnerable; migrate to 12.3(19) or later
  12.2XI	Vulnerable; migrate to 12.3(19) or later
  12.2XJ	Vulnerable; migrate to 12.3(19) or later
  12.2XK	Vulnerable; migrate to 12.3(19) or later
  12.2XL	Vulnerable; migrate to 12.3(19) or later
  12.2XM	Vulnerable; migrate to 12.3(19) or later
  12.2XN	Vulnerable; migrate to 12.3(19) or later
  12.2XQ	Vulnerable; migrate to 12.3(19) or later
  12.2XR	Vulnerable; migrate to 12.3(19) or later
  12.2XS	Vulnerable; migrate to 12.3(19) or later
  12.2XT	Vulnerable; migrate to 12.3(19) or later
  12.2XU	Vulnerable; migrate to 12.3(19) or later
  12.2XV	Vulnerable; migrate to 12.3(19) or later
  12.2XW	Vulnerable; migrate to 12.3(19) or later
  12.2YA	Vulnerable; migrate to 12.3(19) or later
  12.2YB	Vulnerable; migrate to 12.3(19) or later
  12.2YC	Vulnerable; migrate to 12.3(19) or later
  12.2YD	Vulnerable; migrate to 12.3(11)T11 or later
  12.2YE	Vulnerable; migrate to 12.2(25)S12 or later; Available 12-Feb-07
  12.2YF	Vulnerable; migrate to 12.3(19) or later
  12.2YG	Vulnerable; migrate to 12.3(19) or later
  12.2YH	Vulnerable; migrate to 12.3(19) or later
  12.2YJ	Vulnerable; migrate to 12.3(19) or later
  12.2YK	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YL	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YM	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YN	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YO	Not vulnerable
  12.2YP	Vulnerable; migrate to 12.3(19) or later
  12.2YQ	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YR	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YS	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YT	Vulnerable; migrate to 12.3(19) or later
  12.2YU	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YV	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YW	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YX	Vulnerable; migrate to 12.4(8) or later
  12.2YY	Vulnerable; migrate to 12.3(4)T13 or later
  12.2YZ	Vulnerable; migrate to 12.2(25)S12 or later; Available 12-Feb-07
  12.2ZA	Vulnerable; migrate to 12.2(18)SXD7a or later
  12.2ZB	Vulnerable; migrate to 12.3(4)T13 or later
  12.2ZC	Vulnerable; migrate to 12.3(4)T13 or later
  12.2ZD	Vulnerable; contact TAC
  12.2ZE	Vulnerable; migrate to 12.3(19) or later
  12.2ZF	Vulnerable; migrate to 12.3(4)T13 or later
  12.2ZG	Vulnerable; contact TAC
  12.2ZH	Vulnerable; contact TAC
  12.2ZJ	Vulnerable; migrate to 12.3(4)T13 or later
  12.2ZL	Vulnerable; contact TAC
  12.2ZN	Vulnerable; migrate to 12.3(4)T13 or later
  12.2ZP	Vulnerable; migrate to 12.4(8) or later
  Affected 12.3-Based Release	Rebuild	Maintenance
  12.3	12.3(10f)	12.3(19)
  12.3B	Vulnerable; migrate to 12.3(11)T11 or later
  12.3BC	12.3(13a)BC6
  	12.3(17a)BC2
  12.3BW	Vulnerable; migrate to 13.3(11)T11 or later
  12.3JA	12.3(8)JA2
  12.3JEA	All 12.3JEA releases are fixed
  12.3JEB	All 12.3JEB releases are fixed
  12.3JK	12.3(2)JK2
  12.3JX	12.3(7)JX4	12.3(11)JX
  12.3T	12.3(4)T13
  	12.3(11)T11
  	Limited platform support is available: Contact TAC
  	Please migrate to 12.4(8) or later
  12.3TPC	Vulnerable; contact TAC
  12.3XA	Vulnerable; contact TAC
  12.3XB	Vulnerable; migrate to 12.3(11)T11 or later
  12.3XC	Vulnerable; contact TAC
  12.3XD	Vulnerable; migrate to 12.3(11)T11 or later
  12.3XE	Vulnerable; contact TAC
  12.3XF	Vulnerable; migrate to 12.3(11)T11 or later
  12.3XG	Vulnerable; contact TAC
  12.3XH	Vulnerable; migrate to 12.3(11)T11 or later
  12.3XI	12.3(7)XI8
  12.3XJ	Vulnerable; migrate to 12.3(14)YX2 or later
  12.3XK	Vulnerable; migrate to 12.4(8) or later
  12.3XQ	Vulnerable; migrate to 12.4(8) or later
  12.3XR	Vulnerable; contact TAC
  12.3XS	Vulnerable; migrate to 12.4(8) or later
  12.3XU	Vulnerable; migrate to 12.4(2)T5 or later
  12.3XW	Vulnerable; migrate to 12.3(14)YX2 or later
  12.3XX	Vulnerable; migrate to 12.4(8) or later
  12.3XY	Vulnerable; migrate to 12.4(8) or later
  12.3YA	Vulnerable; contact TAC
  12.3YD	Vulnerable; migrate to 12.4(2)T5 or later
  12.3YF	Vulnerable; migrate to 12.3(14)YX2 or later
  12.3YG	Vulnerable; migrate to 12.4(2)T5 or later
  12.3YH	Vulnerable; migrate to 12.4(2)T5 or later
  12.3YI	Vulnerable; migrate to 12.4(2)T5 or later
  12.3YJ	Vulnerable; migrate to 12.3(14)YQ8 or later
  12.3YK	Vulnerable; migrate to 12.4(4)T4 or later
  12.3YM	12.3(14)YM8
  12.3YQ	12.3(14)YQ8
  12.3YS	Vulnerable; migrate to 12.4(4)T4 or later
  12.3YT	Vulnerable; migrate to 12.4(4)T4 or later
  12.3YU	Vulnerable; contact TAC
  12.3YX	12.3(14)YX2
  12.3YZ	12.3(11)YZ1
  Affected 12.4-Based Release	Rebuild	Maintenance
  12.4	12.4(3e)
  	12.4(7b)	12.4(8)
  12.4MR	12.4(6)MR1
  12.4SW	All 12.4SW releases are fixed
  12.4T	12.4(2)T5
  	12.4(4)T4
  	12.4(6)T3	12.4(9)T
  12.4XA	Vulnerable; migrate to 12.4(6)T3
  12.4XB	Vulnerable; contact TAC
  12.4XC	12.4(4)XC3
  12.4XD	12.4(4)XD4
  12.4XE	All 12.4XE releases are fixed
  12.4XG	All 12.4XG releases are fixed
  12.4XJ	All 12.4XJ releases are fixed
  12.4XP	All 12.4XP releases are fixed
  12.4XT	All 12.4XT releases are fixed

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

  This vulnerability was discovered by Cisco during our internal testing process.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070124-crafted-tcp

Revision History

• Revision 1.2	2007-February-02	Updated the12.1EO entry in the Software Version and Fixes table.
  1.1	2007-January-30	BGP and MD5 update.
  1.0	2007-January-24	Initial public release.

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